Hall effect magnetic field sensing elements are known. As is known, a Hall effect element includes a so-called “Hall plate,” which is most often an epi region (i.e., layer) upon a substrate. An epi region will be understood to have a medium amount of doping, described more fully below. Above the epi region is a field plate having generally the same outline or perimeter as the Hall plate. The field plate is made of metal or polysilicon. Between the Hall plate and the field plate is disposed an isolation layer, for example, a field oxide or a nitride layer.
Referring to FIG. 1, a conventional square Hall effect element 10 has a square perimeter 14. A cross section of the Hall effect element 10 will be understood by those of ordinary skill in the art, but is the same as or similar to a cross section shown in FIG. 4.
The conventional square Hall effect element 10 has four electrical contacts 12a-12d. As is known, in operation, a voltage is applied to opposite electrical contacts, e.g., 12a and 12c, (or, more particularly, to metal upon the electrical contacts) and an output voltage proportional to a magnetic field experienced by the Hall effect element 10 is generated between the other opposite electrical contacts, e.g., 12b and 12d. 
In some arrangements, the Hall effect element 10 is used in a so-called “chopped” arrangement by associated electronics. In the chopped arrangement, sequentially, different sets of opposing electrical contacts are selected to drive the Hall effect element and output signals are received from the other sets of opposing electrical contacts. The resulting several output signals are averaged or in some other way combined. The resulting combined signal tends to have less offset voltage than any one output signal taken alone.
The perimeter 14 is representative of both a perimeter of the Hall plate, i.e., epi region, and also a perimeter of the field plate. A boundary 16 is representative of a field oxide extension beyond the edge of the perimeter 14.
Referring now to FIG. 2, a conventional cross-shaped Hall effect element 20 has a cross-shaped perimeter 22. It will be apparent that a conventional cross-shaped perimeter 22 has particular shape characteristics. For example, the perimeter 22 has four indented regions of which an indented region 28 is but one example. Taking the indented region 28 as representative of all of the indented regions, the indented region 28 has two sides 30, 32 forming a V-shape. An angle 34 between the two sides 30, 32 is ninety degrees. The cross-shaped perimeter 22 also has four corner regions, for example, a corner region 24 comprising two sides 24a, 24b, each side with a length 26. The cross-shaped perimeter 22 also has a square central core region 36. Lengths of the sides of the central core region 36, represented by a dimension 38, are each the same as a width of one of the arms of the cross.
The conventional cross-shaped Hall effect element 20 has four electrical contacts 38a-38d. Operation of the Hall effect element 20 is the same as or similar to operation of the Hall effect element 10 of FIG. 1.
In general, the cross-shaped Hall effect element 20 has certain advantages when compared with the square Hall effect element 10 of FIG. 1. In particular, the cross-shaped Hall effect element 20 of similar size to the square Hall effect element 10 uses less area than the square Hall effect element 10 of FIG. 1. Less area can result in higher device yield and also a smaller die on which the Hall effect element 20 is disposed, particularly when combined with other component on the same substrate. Less area also tends to result in lower capacitance, which tends to reduce response time.
In contrast, the square Hall effect element 10 of FIG. 1 has certain advantages when compared with the cross-shaped Hall effect element 20. In particular, the square Hall effect element 10 of similar size to the cross-shaped Hall effect element 20 has both higher sensitivity to magnetic fields and also a lower resistance between opposing electrical contacts.
It would be desirable to have a Hall effect element that has all of the above-listed advantages, namely, a smaller area than a square Hall effect element, good sensitivity and low resistance like a square Hall effect element, with low capacitance and fast response time like the cross-shaped Hall effect element.